This invention relates to a method for separating a continuous stream of connected business forms or like web products into exact count zig-zag folded stacks so as to provide the same for packaging. With the ever increasing use of computers, sizable volumes of business forms are used daily. These forms are normally provided in accordion or zig-zag folding along transverse lines of perforation. Also, it is the normal practice to equip the continuous web or webs making up the business forms with control margins having line holes for engagement with pin belts on the computer printout.
In the manufacture of such zig-zag folded forms, the webs are processed at high speed (of the order of 1500 feet per minute) from parent rolls. The web material wound into the parent rolls may have been printed previously or may be printed on the business form machine. In addition, the business form machine will provide the line holes making up the control margins and cross perforate the web or webs to define the individual business forms. At the end of the business form machine, a zig-zag folder is provided which delivers a stream of accordion pleated forms. In the past, a machine operator has had to be positioned at the output side of the ziz-zag folder to burst the web material every so often so as to separate the zig-zag folded forms into stacks handleable for cartoning. For example, a normal carton will accommodate about 3,000 business forms. With the business forms having popular lengths of 81/2 or 11", it will be apparent that at the speeds contemplated, this separation occurs every few minutes. To give the operator some idea of where the separation is to occur, the practice has been to apply a stripe of ink along one of the control margins during the process of manufacture. Because the web material is traveling at such high speed, it is virtually impossible to limit this stripe to a specified or given or line of cross perforation. In fact, the stripe, even if applied carefully, normally extends over several business forms and it has been the practice for the operator to select the line of cross perforation approximately midway of the length of this stripe. The operator then utilizes a dull knife or similar shearing instrument to slash through the zig-zag forms and separate the same into stacks. It will be immediately apparent that this established procedure does not result in "exact count" stacks. Further, it is time-consuming and expensive in requiring the continuous attention of the operator.
According to the invention, these problems are avoided and by performing the bursting at a time and place not heretofore known, i.e., before the web goes into the zig-zag folding station. The web is literally "burst" along a line of cross perforation which is pre-selected to yield an exact count, viz., 3,000 business forms, for example. In the illustrated embodiment, this is achieved by simultaneously nipping the web between two sets of rolls, the first set running at web speed while the second, or downstream set, runs faster than the web speed. Thus, the downstream set of rolls applies a tension stress to the web to burst the same along a line of cross perforation that is located between the two sets of rolls.
The basic idea of "bursting" utilizing two sets of rolls is not new in itself. This is conventionally employed on the downstream side of the computer where the web material is burst at every cross perforation -- as in the case of providing insert mailers. However, it is believed unknown to selectively burst a business form web at a few widely spaced pre-selected points in conjunction with the preparation of the same for zig-zag folding.
According to the invention, optimum results are achieved by using arcuate pads for the bursting rolls so as to avoid any possibility of marking, ironing or wrinkling the web material. The arcuate pad idea for selective bursting is in itself known as can be seen in co-owned patent No. 3,498,558. However, again there has been no appreciation of the merit of utilizing this construction and operation in a machine and method for developing exact count zig-zag folded business forms.